Method for isomerizing alpha olefins to beta olefins with chromium nickel phosphate



Aug. 30, 1966 c. R. NoDDiNGs ETAL 3,270,085

METHOD FOR ISOMERIZING ALPHA OLEFINS TC BETA OLEFINS WITH CHROMIUM NICKEL PHOSPHATE Filed Jan. 6, 1964 BY Rona/d 6. Galles United States Patent O METHD FOR ISOMERIZNG ALPHA OLEFINS T BETA OLEFINS WITH CHROMIUM NICKEL PHSPHATE Charles R. Noddings, Midland, and Ronald G. Gates, Breckenridge, Mich., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Jan. 6, 1964, Ser. No. 335,830 2 Claims. (Cl. 260-683.2)

This invention concerns a new catalyst and a process employing `the catalyst for the isomerization of alpha olens having four or more carbon atoms in the molecule to beta olens.

It is, of course, well Iknown that aliphatic hydrocarbons, eg., petroleum fractions (mixed hydrocarbons) or individual paraiiins or olelins, can be pyrolyzed to obtain a mixture of products comprising a small, though appreciable, proportion of conjugated diolelins and a larger proportion of shorter chain length unsaturate products. However, -it is unusual to find .among those materials capable of complex compound `formation and which in such form are dehydrogenation and/ or cracking catalysts one group or complexes which are also capable of isomerizing alpha olelins to beta olefns in near quantitative yields.

It `is an object `of this invention to provide an improved method ifor the isomerization of .alpha C4 and yhigher olelinic hydrocarbons to their beta isomers. Another object of the present invention is to provide such a method whereby useful organic products (that is products other than CO2, carbon and hydrogen `from the isomerization) are obtained in quantities which lincrease the economical value of the products over that of the starting carbon compounds. A further object is to provide a set -of operating conditions under which the new catalyst may effectively be used for the foregoing purposes. Other objects will be apparent from the following description of the invention.

We have found that a chromium-nickel phosphate prepared in the manner of our copend'ing application filed even date herewith, entitled Chromium Nickel Phosphate Catalyst and Method for -Dehydrogenating and Cracking Alkanes and Oleiins, is effective for the isomerization of l-C4 and higher alkenes to `their beta isomer when the hydrocarbon is contacted with the catalyst at from 100 to about 300 C.

The catalyst is prepared -by lmixing together watersoluble metal salts of chromium and nickel with a water- `soluble form of the ortho-phosphate moiety (P045) in an aqueous medium under conditions such that the pH is within the range of `from 4 to l0. By this reference applicants incorporate the description yand examples of said copending application relative to catalyst production.

C4 an-d higher hydrocarbons can be isomerized in the presence of the catalyst of the present invention at temperatures between 100 and 300 C., land in some instances at temperatures as tmuch as 50 C. above this range. The reaction is advantageously carried out at ternperatures between 200 and 280 C.

Except for the foregoing limitations, the conditions under 'which the isomerization reaction is carried out may be varied widely. Also, the method is operable at atmospheric, subatmospheria or at superatmospheric pressures, provided the hydrocarbon reactant is in vapoized form. In some instances, the yield of isomerized product decreases upon increase o-f the reaction pressure above atmospheric. However, the ability to operate at an increased pressure is of considerable advantage, since oondensation of the reaction products lmay thereby be facilitated. In general, the proportion of hydrocarbon reacted and also `the amount of by-product formation per pass 3,2 70,085 Patented August 30, 1966 through the catalyst bed tend to decrease with increase in the rate of vapor flow, and vice versa.

In producing isomerized hydrocarbon products in accordance 'with the invention, a reaction chamber is charged with the granular catalyst and the lubricant employed is 1removed from the catalyst. This is usually accomplished by passing an O2-containing gas such as oxygen or air, preferably `a mixture of about equal volumes of air and steam, through `the catalyst bed at a high temperature, e.g., 450 to 750 C. 4When the lubricant used in preparing the catalyst granules is a substance capable of being vaporized, e.g., a mineral or Vegetable oil, the step of treating the catalyst with air may be preceded by one of passing an inert gas or vapor `such as steam, nitrogen, or carbon dioxide over the catalyst so as to vaporize at least a portion of the binding agent from the catalyst granules.

Alfter freeing the catalyst of the lubricant, the catalyst bed is swept free of the O2 lor air with steam and is heated to the desired reaction temperature, preferably by passing superheated steam through the same. The hydrocarbon reactant, e.g., butylene, amylene, hexylene, or heptylene, having at least 4 carbon atoms is then passed through the catalyst bed at a temperature between and 300 C., and preferably between 200 anfd 280 C. The usual procedure is to lpass the hydrocarbon gas which has been superheated to 100 C. or above, i.e., to the desired reaction temperature through the bed of catalyst. However, the heat may be supplied on other ways, e.g., by externally heating the catalyst chamber itself. As hereinbefore mentioned, the rate of vapor flow through the catalyst chamber may 'be varied widely, but in practice the flow usually corresponds to Abetween 100 and 700 liters Vof the hydrocarbon (expressed .as at 0 C. and 760 millimeters pressure) per liter of catalyst bed per hour.

The vapors issuing from the catalyst chamber are ordinarily passed through heat exchangers and other cooling devices to condense the hydrocarbon products.

During use in the process, the catalyst gradually accumulates a small amount of carbon, or non-volatile organic material, and loses its activity. Accordingly, ow of the 'hydrocarbon starting material is periodically interrupted and air, admixed with the steam, is blown through the catalyst bed, eg., at temperatures between 450 and 700 C., to oxidize and removed the carbonaceous or organic material and thus reactivate the catalyst. Usually several hours are required to carry out this reactivation step. However, if, during compounding of the catalyst intotablet form, 4an lagent having the property of catalyzing the oxidation of carbon is admixed therewith, the time subsequently required for reactivating the catalyst with steam and air may be reduced markedly. For instance, the incorporation of one or two percent -by Weight of chr-omic oxide in `the catalyst tablets facilitates reactivaltion of the catalyst. Other agents having the property of catalyzing the burning of carbon are `known to the art.

After completing the reactivation step, the catalyst chamber is again swept Ifree of air with steam and the introduction of hydrocarbons is` resumed. Usually, reactivation of a catalyst is advisable after several hours of use in the isomerization reaction. In practice, two or more catalyst chambers are preferably employed in a system provided with connections Lfor passing the reaction Imixture alternately through different catalyst beds. One catalyst bed is usually employed in the isomerization reaction `while another is being heated, reactivated and cooled in `consecutive operations. By operating in this manner, the isomerization reaction may be carried out continuously.

The following example illustrates the present invention, but is not to be construed as limiting:

Exm'ple l .-In the manner shown in the following difr' ICC agram, 14.3 gram moles of chromium chloride as an 11.5 weight percent aqueous solution thereof was mixed in a vessel |With 2.38 gram 'moles of nickel chloride as a 29 weight percent aqueous solution and 16.3 gram moles of phosphoric acid as a 71 weight percent aqueous solution .and the resulting mixture is diluted with water to a total volume of 80 gallons. Upon completion o-f the addition of the labove enumerated ychemicals rto the vessel reactor, an aqueous 14.7 weight percent ammonium hydroxide solution was, or had been, added. IIn some instances, the aqueous ammonium ihydroxide was added together with the reactants, in others after addition of all of the reactants, and in still others the phosphoric acid and ammonia vwere flrst mixed and then admixed with the other reactants. The reaction mass was continuously stirred and base or acid added to produce and maintain a pH of lthe system between 4.5 and 7,1. In the specic instance 49.1 gram moles of ammonium hydroxide were required to maintain the pH at 4.5 at the end of 2.5 hours of reaction. The reaction was considered complete when the nal pH remained constant. Thereafter the reaction mass was allowed to settle overnight alfter which the supernatant liquid above the precipitate was drawn off (approximately 58 gallons decanted) and the resulting thick slurry ltered and washed with water. The lltrate was discarded. In the specific instance the slurry was washed by decantation 'with water 14 times until chloride free, then removed and dried at 100 C. in a rotary drier. The dry powder was recovered to the extent of 78% of the theoretical yield, based on the starting materials used, and lwas crushed, mixed with about 2% of a lubricant grade graphite and expressed into pellets about 1A inch in diameter and 1A inch long. The graphite was burned off -by treating `the pellets with air and steam at about 650 C. for about `6 hours. The resulting .catalyst pellets were tested as an isomerization catalyst as outlined in the following table.

4 Table Catalyst Preparation Data:

Mole ratio Cr/Ni 6.0 9. 0 6.0

pH o precipitation 4. 5 4. 5 G. 0 Alkene Isomerization:

Feedstock, 93% butene-l v./v. hr., S.T.P 286 344 320 Temperature, C 200 216 200 Product Data:

Percent conversion per pass 74 77 64 Percent yield ot 2-butene based on l-butene converted 100 100 100 We claim:

1. The method which comprises isomerizing alpha olelnic hydrocarbons having at least 4 carbon atoms to their corresponding lbeta isomers which comprises passing t-he hydrocarbon at a temperature between 100 and 300 C. in lcontact with a :catalyst composed of a metal phosphate material consisting essentially of phosphate radicals chemically combined 'with chromium and nickel in the relative proportions of between 6 and 12 atoms of chromium per atom lof nickel which metal phosphate material is preparable Iby mixing a solution of soluble salts of chromium and nickel With a `solution of a soluble orthophosphate and precipitating said metal phosphate material Ifrom the mixture at a pH of between about 4 to 10.

2. The method of lclaim 1 which comprises passing hydrocarbon vapors containing butene-l into contact with said catalyst.

References Cited by the Examiner UNITED STATES PATENTS 2,281,804 5/ 1942 Ruthluff 260-6832 2,336,600 12/1943 Fawcett 260--6832 2,442,320 5/ 1948 Britton et al 260-681 DELBE-RT E. GANTZ, Primary Examiner.

R. H. SHUBERT, Assistant Examiner. 

1. THE METHOD WHICH COMPRISES ISOMERIZING ALPHA OLEFINIC HYDROCARBONS HAVING AT LEAST 4 CARBON ATOMS TO THEIR CORRESPONDING BETA ISOMERS WHICH COMPRISES PASSING THE HYDROCARBONS AT A TEMPERATURE BETWEEN 100* AND 300*C. IN CONACT WITH A CATALYST COMPOSED OF A METAL PHOSPHATE MATERIAL CONSISTING ESSENTIALLY OF PHOSPHATE RADICALS CHEMICALLY COMBINED WITH CHROMIUM AND NICKEL IN THE RELATIE PROPORTIONS OF BETWEEN 6 AND 12 ATOMS OF CHROMIUM PER ATOM OF NICKEL AND WHICH METAL PHOSPHATE MATERIAL IS PREPARABLE BY MIXING A SOLUTION OF SOLUBLE SALTS OF CHROMIUM AND NICKEL WITH A SOLUTION OF SOLUBLE ORTHOPHOSPHATE AND PRECIPITATING SAID METAL PHOSPHATE MATERIAL FROM THE MIXTURE AT A PH OF BETWEEN ABOUT 4 TO
 10. 